Interested in reducing clutter and mislabelling in areas I have an interest, I wonder if these little-used tags should be removed. (This is my first meta post - please be gentle)
doxygen-addtogroup is an incredibly specific sub-tag and not even all of the 6 questions so tagged are relevant to the tag.
Neither of the above have an description, and have a total of 3 followers between them.
As far as I can tell all the Doxygen sub-tag questions also have the Doxygen tag which is plenty. If there is a need to 'sub class' doxygen questions it's most effectively done with a language tag for the language being documented.